Marriage vote draws questions on turnout

Josh Frydenberg won't join a same -sex marriage campaign but will urge his electorate to vote yes.

Senior Liberal Josh Frydenberg says he supports same-sex marriage and will be encouraging as many people as possible in his electorate to participate in the postal plebiscite and vote "yes".

"But when it comes to my broader position in terms of campaigning on this issue, I have bigger fish to fry and that is energy policy and that will be my priority in the weeks and the months ahead," he told Sky News on Sunday.

The energy minister said if a 'no' vote gets up, the prime minister has said the government won't be bringing to the parliament a private members bill and a free vote on the issue.